This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Pulmonary arterial hypertension (PAH) is a devastating disease with a usually fatal outcome There is as yet no reliable treatment for PAH, largely because the biochemical cause and course remain unknown.There are no adequate animal models. We are undertaking proteomics investigations of tissues from affected individuals, in order to gain knowledge about the pathways that are affected in conjunction with the disease.